Divergent Microbial Nitrogen‐Limitation Dynamics Between Primary and Secondary Succession in Subalpine Ecosystems of the Eastern Tibetan Plateau

Summary

This study examined how microbial nitrogen limitation dynamics diverge between primary succession (20–130 years following glacier retreat) and secondary succession (grassland to forest transition) on the eastern Tibetan Plateau. During primary succession, microbial N limitation was progressively relieved as soil carbon, nitrogen and phosphorus accumulated and plant communities developed, whereas late-stage secondary coniferous forests experienced N limitation driven by reduced soil N mineralisation and homogeneous vegetation. The findings suggest that succession-specific management strategies are needed to conserve soil nitrogen cycling and ecosystem resilience in fragile subalpine systems.

UK applicability

This study examines subalpine post-glacial and successional ecosystems specific to the Tibetan Plateau's climate and vegetation dynamics. Whilst the mechanistic insights into microbial N limitation and soil development may inform understanding of UK upland and montane soil processes, the findings have limited direct applicability to managed UK agricultural or pastoral systems, which operate under different edaphic and climatic conditions.

Key measures

Microbial N limitation status, gross and net N mineralization rates, soil labile carbon and total nitrogen and phosphorus pools, ureC gene abundance, 4-β-N-acetylglucosaminidase activity, leucine aminopeptidase activity, plant biomass and richness, soil pH

Outcomes reported

The study quantified microbial nitrogen metabolism and gross nitrogen transformations across primary succession (post-glacier retreat) and secondary succession (grassland to forest) using vector modelling, GeoChip 5.0 analysis, and 15N-tracer methods. Key findings included progressive alleviation of microbial N limitation during primary succession and emergence of N limitation in late coniferous secondary succession stages.

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